Sea-level rise is only one of the climate-driven threats that are making the world more dangerous and volatile. Drought contributed to the escalating food prices that triggered the Arab Spring revolt in Egypt, in 2011; it also helped trigger the civil war in Syria. In northern Nigeria, a region destabilized by extreme cycles of drought and flooding, Boko Haram is terrorizing villages and killing thousands of Nigerians…

As the world warms, the U.S. military will inevitably be called upon to conduct more disaster relief and humanitarian-aid missions. The U.S. military… also prides itself on its practical-mindedness, both in times of war and of peace. Military leaders embraced desegregation long before the rest of the nation, in part because they wanted the best people they could find, no matter what color. "It's our job to deal with the world as it is, not as we wish it could be," says Robert Freeman, a meteorologist and member of the Navy's climate-change task force.